1. Field
The present disclosure relates generally to wireless communication system. More specifically the present disclosure related to methods and apparatus for enhanced sleep mode tiering to optimize standby time and test yield.
2. Background
Wireless communication devices have become smaller and more powerful as well as more capable. Increasingly users rely on wireless communication devices for mobile phone use as well as email and Internet access. At the same time, devices have become smaller in size. Devices such as cellular telephones, personal digital assistants (PDAs), laptop computers, and other similar devices provide reliable service with expanded coverage areas. Such devices may be referred to as mobile stations, stations, access terminals, user terminals, subscriber units, user equipments, and similar terms.
A wireless communication system may support communication for multiple wireless communication devices at the same time. In use, a wireless communication device may communicate with one or more base stations by transmissions on the uplink and downlink. Base stations may be referred to as access points, Node Bs, or other similar terms. The uplink or reverse link refers to the communication link from the wireless communication device to the base station, while the downlink or forward link refers to the communication from the base station to the wireless communication devices.
Wireless communication systems may be multiple access systems capable of supporting communication with multiple users by sharing the available system resources, such as bandwidth and transmit power. Examples of such multiple access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, wideband code division multiple access (WCDMA) systems, global system for mobile (GSM) communication systems, enhanced data rates for GSM evolution (EDGE) systems, and orthogonal frequency division multiple access (OFDMA) systems.
Aggressive sleep mode voltages are needed in order to maximize battery life of a system on chip (SoC). All SoCs have a specification defined for sleep mode operating voltage and sleep mode voltage. The sleep mode must meet certain specifications. In order to ensure that the specification is met a higher voltage threshold for the sleep mode voltage ends up being used so as to ensure that the greater majority of tested SoCs will meet the voltage specification, as it is easier to meet a higher voltage sleep requirement. Sleep mode voltage affects data retention during the sleep period, and data retention is improved when the voltage is higher. A lower voltage allows for a longer sleep duration. However, because of the desire to utilize most of the SoCs being tested, the sleep mode voltage is set higher than many devices need. This is becoming more and more important as smartphones and other personal devices run greater numbers of applications, which require significant amounts of battery power. Silicon and process variation may not permit the same value to be implemented across all devices because some of the population of devices may fail at that value.
There is a need in the art for methods and apparatus for enhanced sleep mode tiering to optimize time and test yield.